Process of manufacturing incandescent bodies.



' into light, the greater PATENT OFFICE,

UNITED ST TES CARL KELLNER, OF VIENNA, AUSTRIA-HUNGARY.

'PROGESS or MANUFACTURING lNCllNDESCENT BODIES.

SPECIFICATION forming part of Letters Patent No. 661,610, dated November13, 1900. Application filed March 23, 1899. Serial No- '7l0,238. (Nospecimens.)

To all whom it may concern.-

Be it known that LOARL KELLNER, a subject of the Emperor of Austria,residing at Vienna, in the Province of Lower Austria, in the Empire ofAustria-Hungary, have in: vented certain new and useful Improvements inIncandescent Bodies for Incandescent Electric Lamps and in the Processof Manufacturing the Same; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

In the heretofore-used incandescent bodies (carbon filaments) ofelectric incandescent lamps only a small partof the energy supplied inthe form of electricity is converted portion being lost in the form ofheat. The cause of this is that such filaments which are made ofamorphous carbon cannot -be heated to an intense white heat, as theywould then be quickly destroyed the conversion of the amorphouscarbon'into graphite of increased density, Which takes place at Whiteheat, altering the molecular structure of the filaments. Ihave foundthat this alteration also takes place in the ordinary use ofincandescentlamps, but in a gradual manner, the filament, which isconverted by the ordinary glowing partly into a graphite-likemodification of carbou,being' converted by the continued use of the lampinto denser graphite, with the result that the filament breaks.

Many attempts have been made to discover a better and more durableincandescent body for incandescent electric lamps, and it, has beenrecognized that only those bodies that fuse with the most difilculty'aresuitable for the purpose. No satisfactory practical result, however, hasheretofore been obtained, because either too goodconductors ofelectricity have been tried, in which the resistance necessary forproducing white heat cannot be reached, or because in incandescent.

bodies which are made of mixtures of conduciors and non-conductors (orconductors of the second class) binding or fusing agents have beenemployed which in use have been continuously altered by the electriccurrent, or, finally, because the bodies in order to effect their objecthave first had to be heatedin a tedious manner to that temperature atwhich they become conducting.

Incandescent bodies according to the present invention enable thegreatest portion of the electric energy supplied to be converted intolight, because they can be raised by the electric current to thebrightest white heat without becoming deteriorated. These incandescentbodies consist of infusible metals, which are not very good conductorsof electricity and which have a high capacity for emitting light,such asthorium, or of almost infusible metals, such as-titanium, (in the formof-pure titanium or nitrid of titanium,) chromium, or Wolfram, or alloysof such metals, incandescent bodies made of these in-- fusible or almostinfusible metals or alloys being oxidized at their surfaces, or ofmixtures of (a) almost infusible metals or alloys of the same, or (b)graphite of thekind which offers the very greatest resistance toconversion into graphite acid by potassium chlorate and nitric acid(graphite of high density up to 2.25 specific gravity) with metallicoxids that are infus'ible or are fusible with difficulty and capable ofemitting light, such as thorium oxid, with or without an addition ofcerium oxid.

Incandescent bodies of the kind referred to have the advantage (sincethey possess a relatively small conductivity) that they can be made inconvenient dimensions without being liable to break too easily.

The manufacture of incandescent bodies is effected according to thisinvention by molding the metals of the kind referred to or the mixturesof the difficultly-fusible metals or alloys or graphite of the kindstated with metallic oxids fusible with di'fficulty and capable ofemitting light in a state of fine powder and without the addition of abinding or fusing agent into solid bodies under high pressure. For thispurpose the. dry powder is placed in a press-mold and by means of asuitably-formed plungera considerable pressure (up to twenty thousandkilograms per square centimeter) is exerted upon it.

When the'bodies are made of thorium metal or of metals fusible withdifficulty-such as titanium, chromium, or Wolfram, or alloys of suchmetals alone-they are oxidized at their surfaces by being made to glowin the air by immersion in an oxidizing liquidv or by being inserted asan anode in an electric circuit,

which decomposes an electrolyte of which oxygen is the anion or by anyother suitable means. The thin layer of oxid adheres so firmly to themetal that it is not damaged when the incandescent body is used.

When the incandescent body is to consist of a mixture of graphite ofhigh density with metallic oxids, it may be made by molding and pressinga mixture consisting of powdered metallic oxids capable of emittinglight and of a small addition of cellulose soaked in chlorid of zinc.After glowing in a vacuum or in a neutral gas, such as nitrogen, thebody is subjected to a current of high potential for the purpose ofconverting the amorphous carbon into graphite of high density before theincandescent body is put into use. Disintegration of the body during theconversion of the carbon into graphite is not to be feared, because thesmall quantity of the latter (at most five per cent.) is inclosed by theparticles of metallic oxid.

In order to prevent the incandescent bodiesof the kind described frombeing damaged when in use by excessive heating at the parts where thecurrent is supplied to them-viz., at the places of contact-it isadvisable to strengthen them at such parts-that is to say, to make themthicker-and to mold the lead in g-in wires into the mass of theincandescent bodies when the latter are being molded or to -iuse thesaid wires into the said strengthened parts by means of the electricarc.

I claim- 1. Thei'mprovement in the manufacture of incandescible bodies,which consists in drymolding into the desired shape an infusible orsubstantially infusible metal of inferior conductive and highilluminating power and then surface-oxidizing the body so obtained, forthe purpose set forth.

2. An incandescible body consisting of an inf usible or substantiallyinfnsible metal of inferior conductive and high illuminating power andhaving its surface coated with an oxid of said metal or metals, for thepurpose set forth. y

3. An incandescible body made of a mixture of nitrid of titanium-andhigh-resistance refractory oxid's, substantially as set forth.

4. The manufacture ofincandescible bodies which consists in forming suchbodies of alloys of high-resistance metals and surface-oxidizing thecompleted body, substantially as described.

5. The manufacture of incandescible bodies which consists in forming thesame of a mixture of refractory oxids, cellulose and chlorid of zinc,drying and flashing, substantially as described.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two subscribing witnesses.

CARL KELLNER.

Witnesses:

ALVESTO S. HOGUE, AUGUST FUGGER.

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